Think of Yellowstone as a gigantic pressure cooker, fueled by a massive supervolcano. Water from rain and snowmelt, much of it centuries-old, percolates through cracks in the Earth’s crust until heated by molten rock reservoirs deep below. The water then filters upward, eventually finding release in the thousands of geysers, hot springs, and other hydrothermal wonders.

Eruptions of this supervolcano expel so much material that the crust caves in, creating a craterlike depression called a caldera.

Yellowstone is known as a supervolcano because of the violence and size of its explosions.

The plume of hot rock has been calculated at more than 600 miles deep. But scientists suspect it actually descends as far as 1,800 miles, all the way to what’s known as the Earth’s outer core-mantle boundary.

The reservoirs and plume are superheated, spongelike rock holding pockets of molten material called magma. The reservoirs’ heat, which originates in the plume, is what keeps the area’s geysers boiling.

Ancient rain and snowmelt seep down to just above the volcano’s magma reservoirs, until they are superheated and rise again through the fractures. Volcanic heat and gases help propel steam and water toward the surface, where they escape through hot springs or geysers.

Hot water rises from a deep reservoir into a teapot-shaped chamber. As water and gases fill the sealed space, pressure builds, preventing boiling. Some water spills into the spout, releasing pressure and allowing the water in the chamber to boil. Steam and water then blast up the spout.

Pressure builds behind a narrow constriction until steam shoots through. Some water splashes out, then jets of steam and water explode, rising on average 130 feet. As the chamber drains, pressure drops, and the process begins again.

Highest recorded eruption – 184ft

Eruptions per day on average – 17

Minutes length of eruption – 1.5 to 5

The park’s hydrothermal features cluster in basins at the margins of lava flows or near faults. Rivers and streams are heated as they pass through these basins. Heat and escaping gases are also evidence of the subterranean forces that lie below Yellowstone.

Hundreds of cubic miles of ash, rock and lava would be blasted into the atmosphere, and this would likely plunge much of the northern hemisphere into several days of complete darkness. Virtually everything within 100 miles of Yellowstone would be immediately killed, but a much more cruel fate would befall those living in major cities outside of the immediate blast zone such as Salt Lake City and Denver.

Hot volcanic ash, rock and dust would rain down on those cities literally for weeks. In the end, it would be extremely difficult for anyone living in those communities to survive. In fact, it has been estimated that 90 percent of all people living within 600 miles of Yellowstone would be killed.

Experts project that such an eruption would dump a layer of volcanic ash that is at least 10 feet deep up to 1,000 miles away, and approximately two-thirds of the United States would suddenly become uninhabitable. The volcanic ash would severely contaminate most of our water supplies, and growing food in the middle of the country would become next to impossible.

In other words, it would be the end of our country as we know it today.

The rest of the planet, and this would especially be true for the northern hemisphere, would experience what is known as a “nuclear winter”. An extreme period of “global cooling” would take place, and temperatures around the world would fall by up to 20 degrees. Crops would fail all over the planet, and severe famine would sweep the globe.